/*
Copyright 2022 The Karmada Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package storage

import (
	"context"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apiserver/pkg/registry/generic"
	genericregistry "k8s.io/apiserver/pkg/registry/generic/registry"
	"k8s.io/apiserver/pkg/registry/rest"
	"sigs.k8s.io/structured-merge-diff/v4/fieldpath"

	searchapis "github.com/karmada-io/karmada/pkg/apis/search"
	searchregistry "github.com/karmada-io/karmada/pkg/registry/search"
)

// ResourceRegistryStorage includes storage for ResourceRegistry and for all the subresources.
type ResourceRegistryStorage struct {
	ResourceRegistry *REST
	Status           *StatusREST
}

// NewResourceRegistryStorage returns a ResourceRegistryStorage object that will work against resourceRegistries.
func NewResourceRegistryStorage(scheme *runtime.Scheme, optsGetter generic.RESTOptionsGetter) (*ResourceRegistryStorage, error) {
	strategy := searchregistry.NewStrategy(scheme)

	store := &genericregistry.Store{
		NewFunc:                  func() runtime.Object { return &searchapis.ResourceRegistry{} },
		NewListFunc:              func() runtime.Object { return &searchapis.ResourceRegistryList{} },
		PredicateFunc:            searchregistry.MatchResourceRegistry,
		DefaultQualifiedResource: searchapis.Resource("resourceRegistries"),
		// NOTE: singular name of the resource must be all lowercase.
		SingularQualifiedResource: searchapis.Resource("resourceregistry"),

		CreateStrategy:      strategy,
		UpdateStrategy:      strategy,
		DeleteStrategy:      strategy,
		ResetFieldsStrategy: strategy,

		// TODO: define table converter that exposes more than name/creation timestamp
		TableConvertor: rest.NewDefaultTableConvertor(searchapis.Resource("resourceRegistries")),
	}

	options := &generic.StoreOptions{RESTOptions: optsGetter, AttrFunc: searchregistry.GetAttrs}
	if err := store.CompleteWithOptions(options); err != nil {
		return nil, err
	}

	statusStrategy := searchregistry.NewStatusStrategy(strategy)
	statusStore := *store
	statusStore.UpdateStrategy = statusStrategy
	statusStore.ResetFieldsStrategy = statusStrategy

	resourceRegistryRest := &REST{store}
	return &ResourceRegistryStorage{
		ResourceRegistry: resourceRegistryRest,
		Status:           &StatusREST{&statusStore},
	}, nil
}

// REST implements a RESTStorage for ResourceRegistry.
type REST struct {
	*genericregistry.Store
}

// StatusREST implements the REST endpoint for changing the status of a ResourceRegistry.
type StatusREST struct {
	store *genericregistry.Store
}

// New returns empty ResourceRegistry.
func (r *StatusREST) New() runtime.Object {
	return &searchapis.ResourceRegistry{}
}

// Get retrieves the object from the storage. It is required to support Patch.
func (r *StatusREST) Get(ctx context.Context, name string, options *metav1.GetOptions) (runtime.Object, error) {
	return r.store.Get(ctx, name, options)
}

// Update alters the status subset of an object.
func (r *StatusREST) Update(ctx context.Context, name string, objInfo rest.UpdatedObjectInfo, createValidation rest.ValidateObjectFunc, updateValidation rest.ValidateObjectUpdateFunc, _ bool, options *metav1.UpdateOptions) (runtime.Object, bool, error) {
	// We are explicitly setting forceAllowCreate to false in the call to the underlying storage because
	// subresources should never allow create on update.
	return r.store.Update(ctx, name, objInfo, createValidation, updateValidation, false, options)
}

// GetResetFields implements rest.ResetFieldsStrategy
func (r *StatusREST) GetResetFields() map[fieldpath.APIVersion]*fieldpath.Set {
	return r.store.GetResetFields()
}

// Destroy cleans up its resources on shutdown.
func (r *StatusREST) Destroy() {
	// Given that underlying 'store' is shared with REST,
	// we don't have anything else need to be destroyed.
}
